Exodus 30:11

30:10 And Aaron shall make atonement upon its horns once a year with the blood of the sin offering of atonement; once a year he shall make atonement upon it throughout your generations. It is most holy to the LORD."

30:11 Then the LORD spoke to Moses, saying:

30:12 "When you take the census of the children of Israel for their number, then every man shall give a ransom for himself to the LORD, when you number them, that there may be no plague among them when you number them.